They were made some years ago with a camera build by a friend of mine. It had one lens but two diaphragms and behind those tehre were little mirrors so the image of each diaphragm was split and resulted in two images side by side on a 120 mm roll film. Worked quite good. I have not done 3D macro for some time. But i have been working with another fine trick used on that camera.

These were made with a Nikon D70 and a Leitz photar lens. With the strong magnification you can make with such an objective it is almost impossible to work through the viewfinder. So I made two little pins/needles sticking out in front. The tips of the needles indicate the focal plane and they also give the width of the frame. So when an insect is between the needles it is in focus.

Especially on a digital camera it works well. I'll post an ant with a woodlice. One is a cropped part of the same image to show the details. I can zoom in even further.